The trend of declining birthrate for American White males first started appearing in 2013-14. I remember reading articles on it and began piecing together the causes.
Obama was in office at the time and as part of his "fundamentally change the United States of America" platform, he was allowing floods of illegal aliens (predominately male) and narcotics into the country.
This had two affects: 1. it undercut the wages and job opportunities of middle and lower-class American males and 2. provide excessively dangerous narcotics that would inevitably find its way into the disenfranchised hands of the aforementioned middle and lower-class American males.
More minority males + less White males (less in number and less in economically-providing) = fundamentally change USA. This was what the radical Obama wanted.
When the American public realizes the implications of left-wing progressivism (social justice, anti-colonialism, equity, etc) on the existing population there will be significant consequences.
Please understand that when you see people today justifying Hamas' barbaric brutality on the jewish people of Israel, understand that those people are just waiting to turn that logic on You.